1. Field
This disclosure relates generally to semiconductor processing, and more specifically, to a method for forming an electrical connection between metal layers.
2. Related Art
Conductive vias provide electrical connections between metal lines of an integrated circuit. However, stress migration may result in via failures over time within the integrated circuit. For example, during operation of the integrated circuit, stress migration can cause the accumulation of vacancies within or at a conductive via, which results in the formation of voids which increase the resistance of the conductive via over time. Eventually, the increased resistance due to the vacancies may cause circuit failure. Stress migration may therefore affect long-term operation and reliability of the integrated circuit. The driving force for the migration of vacancies to the via site is the stress gradient. Due to the discontinuity in the metal lines caused by the vias, the stress at the vias is less tensile than in the metal lines to which the vias are connected.